From: Peter Zijlstra <peterz@infradead•org>
To: Boqun Feng <boqun.feng@gmail•com>
Cc: linux-kernel@vger•kernel.org, linuxppc-dev@lists•ozlabs.org,
Ingo Molnar <mingo@kernel•org>,
Benjamin Herrenschmidt <benh@kernel•crashing.org>,
Paul Mackerras <paulus@samba•org>,
Michael Ellerman <mpe@ellerman•id.au>,
Thomas Gleixner <tglx@linutronix•de>,
Will Deacon <will.deacon@arm•com>,
"Paul E. McKenney" <paulmck@linux•vnet.ibm.com>,
Waiman Long <waiman.long@hp•com>
Subject: Re: [RFC 2/5] atomics: introduce arch_atomic_op_{acquire,release,fence} helpers
Date: Fri, 28 Aug 2015 13:36:14 +0200 [thread overview]
Message-ID: <20150828113614.GC16853@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1440730099-29133-3-git-send-email-boqun.feng@gmail.com>
On Fri, Aug 28, 2015 at 10:48:16AM +0800, Boqun Feng wrote:
> Some architectures may have their special barriers for acquire, release
> and fence semantics, general memory barriers(smp_mb__*_atomic()) in
> __atomic_op_*() may be too strong, so arch_atomic_op_*() helpers are
> introduced for architectures to provide their own version helpers to
> build different variants based on _relaxed variants.
>
> Signed-off-by: Boqun Feng <boqun.feng@gmail•com>
> ---
> include/linux/atomic.h | 16 ++++++++++++++++
> 1 file changed, 16 insertions(+)
>
> diff --git a/include/linux/atomic.h b/include/linux/atomic.h
> index 00a5763..622255b 100644
> --- a/include/linux/atomic.h
> +++ b/include/linux/atomic.h
> @@ -34,20 +34,33 @@
> * The idea here is to build acquire/release variants by adding explicit
> * barriers on top of the relaxed variant. In the case where the relaxed
> * variant is already fully ordered, no additional barriers are needed.
> + *
> + * Besides, if an arch has a special barrier for acquire/release, it could
> + * implement its own arch_atomic_op_* and use the same framework for building
> + * variants
> */
> +#ifndef arch_atomic_op_acquire
> #define __atomic_op_acquire(op, args...) \
> ({ \
> typeof(op##_relaxed(args)) __ret = op##_relaxed(args); \
> smp_mb__after_atomic(); \
> __ret; \
> })
> +#else
> +#define __atomic_op_acquire arch_atomic_op_acquire
> +#endif
Not really a fan of this, its not consistent with the existing #ifndef
guard style.
next prev parent reply other threads:[~2015-08-28 11:36 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-28 2:48 [RFC 0/5] atomics: powerpc: implement relaxed/acquire/release variants of some atomics Boqun Feng
2015-08-28 2:48 ` [RFC 1/5] atomics: add test for atomic operations with _relaxed variants Boqun Feng
2015-08-28 2:48 ` [RFC 2/5] atomics: introduce arch_atomic_op_{acquire, release, fence} helpers Boqun Feng
2015-08-28 11:36 ` Peter Zijlstra [this message]
2015-08-28 11:50 ` [RFC 2/5] atomics: introduce arch_atomic_op_{acquire,release,fence} helpers Boqun Feng
2015-08-28 2:48 ` [RFC 3/5] powerpc: atomic: implement atomic{, 64}_{add, sub}_return_* variants Boqun Feng
2015-08-28 10:48 ` [RFC 3/5] powerpc: atomic: implement atomic{,64}_{add,sub}_return_* variants Peter Zijlstra
2015-08-28 12:06 ` Boqun Feng
2015-08-28 14:16 ` Boqun Feng
2015-08-28 15:39 ` Peter Zijlstra
2015-08-28 16:59 ` Boqun Feng
2015-09-01 19:00 ` Will Deacon
2015-09-01 21:45 ` Paul E. McKenney
2015-09-02 9:59 ` Will Deacon
2015-09-02 10:49 ` Paul E. McKenney
2015-09-02 15:23 ` Pranith Kumar
2015-09-02 15:36 ` [RFC 3/5] powerpc: atomic: implement atomic{, 64}_{add, sub}_return_* variants Pranith Kumar
2015-09-03 10:31 ` [RFC 3/5] powerpc: atomic: implement atomic{,64}_{add,sub}_return_* variants Will Deacon
2015-09-11 12:45 ` Will Deacon
2015-09-11 17:09 ` Paul E. McKenney
2015-09-14 11:35 ` Peter Zijlstra
2015-09-14 12:01 ` Peter Zijlstra
2015-09-14 12:11 ` Peter Zijlstra
2015-09-14 15:38 ` Will Deacon
2015-09-14 16:26 ` Paul E. McKenney
2015-08-28 2:48 ` [RFC 4/5] powerpc: atomic: implement xchg_* and atomic{, 64}_xchg_* variants Boqun Feng
2015-08-28 2:48 ` [RFC 5/5] powerpc: atomic: implement cmpxchg{, 64}_* and atomic{, 64}_cmpxchg_* variants Boqun Feng
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